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Advanced Hardware Design (max53)

Ahmedhelmy , 11-11-2018, 01:01 AM
Dear Robert

I finished the part of DDRM 3 with MAX53 please cheek and tell me what is wrong?and please answer this questions
1. how to calculate number of decoupling capacitor for DDRM
1. power supply for voltage divider is 1.5V in Micron reference (TN-46-14)but in i.MX53 System Development
User’s Guide is NVCC_EMI_DRAM what is correct ?
2. Can I put his voltage divider for each DDRM IC or place one Voltage divider for the Max53? And why?
3. why all ports for each data and control swapped in i.MX53 System Development User’s Guide.
4. Which Stack-up is prefer from I.MX53 system Development User's guide or Micron reference? and why difference between them ?
5. How do we calculate number of Layer Need in my PCB's?
6. which Impedance requirements from I.MX53 system Development User's guide or Micron reference? and why difference between as ?
7. how do we calculate Impedance for each Track in my PCB's?



robertferanec , 11-12-2018, 02:22 AM
1. Follow Reference design (use same number as used there) and follow recommendations from design guide (some design guides will tell you how many capacitors you need to use). I do not calculate it - if you really would like to know what is going on on your board you would need to do PDN analysis and simulate it.

2.1 You just need stable 1.5V, how it is generated is not important. However it should be tight up to the memory power, so it follows it.
2.2 Ideally the voltage should be same on all the chips and CPU. if you use more dividers then the tolerance in resistors may cause difference between the voltages - you do not want that. So Ideally you need only one voltage divider and output from this is connected to all the memory chips and cpu.
2.3 please could you attach a screenshot to clarify this question? Usually data and control are swapped for better and easier memory layout.
2.4 - 2.5 designer will decide on stackup: This may help: https://www.fedevel.com/welldoneblog...m-pcb-stackup/
2.6 Usually I follow design guides of the CPU manufacturer with higher priority comparing to design guides of the other chips
2.7 You need to ask your PCB manufacturer or re-use some existing stackups. Only PCB manufacturer can give you the exact track geometry for specific stackup, you only can calculate it approximately. This may help: https://www.fedevel.com/welldoneblog/?s=stackup

Please, I do not check individual files (that would be too complicated as I would then receive many files to check), but you can attach screenshots - if there is something really wrong I will point it out.
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